PostgreSQL : How to check parameter values in postgresql

As part of some basic administration in PostgreSQL databases, we will learn how to check and modify parameters 

there are a few ways to do it

• using the "Show" command
• querying pg_settings catalog
• by directly checking configuration files

 

Assume you need to check the parameter related to the hba_configuration file, like the location of this file but you are not  sure about the parameter name, I just tried with a few options, and it was not giving me proper value, however, it was throwing syntax error like below

 

postgres-# show hba_config;

ERROR:  syntax error at or near "show"

LINE 2: show hba_config;

        ^

postgres=#

 

postgres=# show hba;

ERROR:  unrecognized configuration parameter "hba"

postgres=#

 

for using the "show" command, you must know the exact name of the parameter, or else you can simply use pg_settings catalog to fetch it, I just tried the "like" parameter in pg_settings

 

postgres=# SELECT name, setting, reset_val  FROM pg_settings where name like '%hba%';

   name   |                     setting                     |                    reset_val

----------+-------------------------------------------------+-------------------------------------------------

 hba_file | C:/Program Files/PostgreSQL/10/data/pg_hba.conf | C:/Program Files/PostgreSQL/10/data/pg_hba.conf

(1 row)

 

now you can check using the "show" command

 

postgres=# show hba_file;

                    hba_file

-------------------------------------------------

 C:/Program Files/PostgreSQL/10/data/pg_hba.conf

(1 row)

 

 

postgres=# show max_connections;

 max_connections

-----------------

 100

(1 row)

 [Also Read - Installation of PostgerSQL]